The field of the present invention is systems for screening, the screens thereof and mechanisms attendant thereto.
Vibratory separators have long been used for separation of materials, both wet and dry. Such separators have been classically divided into rectangular screen separators and circular screen separators. An example of a rectangular screen separator is illustrated in U.S. Pat. No. 4,582,597, the disclosure of which is incorporated herein by reference. A circular separator is illustrated in U.S. Pat. No. 4,613,432, the disclosure of which is incorporated herein by reference. Each type of separator has its own advantages well known in the industry.
Vibratory separators may also be distinguished by the multiple ways that they provide tensioned screen cloth. One system is to employ untensioned screens using hook strips in association with tensioning mechanisms on the screening system. One such system is illustrated in U.S. Pat. No. 5,221,008. Alternatively, pretensioned screen panels including tensioned screen cloth affixed to rigid frames provide the tensioning mechanism. In such circumstances, tensioning mechanisms on the vibratory separators are avoided. The manufacture of such screens is disclosed in U.S. Pat. No. 4,968,366, the disclosure of which is incorporated herein by reference.
Hook strip screens which are tensioned on the screening device require a crown on the screen bed. Such a crown has proven to be disadvantageous with regard to the distribution of material on the screen. Such devices also require multiple fasteners along the sides of the screen deck which are time consuming to operate and are susceptible to errors in assembly.
Pretensioned screens have been incorporated into vibratory housings in circular screens by including screen frames with outwardly extending mounting flanges that are sandwiched between succeeding wall portions. Reference is made to U.S. Pat. No. 4,810,372, incorporated herein by reference, illustrating such flanges and their placement in the housing. Pretensioned screens which are rectangular have not employed outwardly extending mounting flanges. They have used clamps operating directly on the frame itself. One clamp system employs a pneumatic seal in association with channels to locate and retain such frames. Reference is made to U.S. Pat. No. 4,582,597 and to U.S. Pat. No. 5,226,546, the disclosures of which are incorporated herein by reference.
The present invention is directed to a system by which rectangular screens are mounted to vibratory screening equipment. The invention contemplates the screens, the mounting arrangement and assembly with a screening system.
In a first separate aspect of the present invention, a screen has a screen frame with screening element affixed thereto. The frame includes a mounting surface toward and being displaced from the screening element designed to allow retention of the screen from below.
In a second separate aspect of the present invention, a mounting frame of a screening system provides a support surface to receive a screen frame. Clips are pivotally mounted relative to the mounting frame with a first lever extending to above the support surface and a second lever extending to below the support surface. Actuators fixed relative to the mounting frame operatively engage the second levers.
In a third separate aspect of the present invention, the actuator of the second aspect includes a contact extending to manipulate the clip. The contact may be driven by an inflatable body positioned with the mounting frame.
In a fourth separate aspect of the present invention, a screen system employs a resiliently mounted housing with a vibration generator mounted thereto. A screen with a screen frame has a mounting surface on the inside of the frame, clips pivotally mounted to the frame with a first lever to engage the a mounting surface on the inside of the frame and actuators to operatively engage the clips. This configuration allows for the easy placement and removal of screens from above with pneumatically actuated clips capable of both holding the screen in position and further tensioning the screen cloth.
In a fifth separate aspect of the present invention, the several foregoing separate aspects are contemplated-to be advantageously employed in combination.
Accordingly, it is an object of the present invention to provide an improved screening system. Other and further objects and advantages will appear hereinafter.